2 slices of thick white bread (per serving)
250g mature cheddar (or a welsh farmhouse cheese if you want to be more traditional)
1 tsp mustard
2 tsp Worcestershire sauce
Cut the centre out of a slice of bread, leaving only the thin crust in one piece - then cut that centre into smaller squares.
Place all of the bread along with another regular full slice on a baking tray and lightly toast under a grill for a few minutes.
Melt the butter in a pot on a medium-low heat, then add the cheese.
Stir it all in until everything is melted.
Stir in the mustard and Worcestershire sauce and remove from the heat.
Stack the hollowed out crust of the bread onto the full slice and drop in half of the small squares.
Fill this with the cheese mixture, then top with whatever squares you have left over.
Put it under the grill for another 1 or 2 minutes until the bread has fully toasted and the cheese mixture is slightly brown.